Welcome to the forum!
Usually we recommend leaving the bottom of your enclosure bare. This makes it:
- easy to clean
- less susceptible to bacteria growth
- less of a risk for impaction of the chameleon
- easier to install a functional drainage system
and many other benefits.
You will end up needing a drainage system if you have a large species (any species besides pygmy chameleons) and they are fairly easy to make.
What are the current dimensions/plans for the cage? Pics?